Method of manufacturing vias with pulsing plasma

ABSTRACT

A method of manufacturing a semiconductor includes: providing a stacked structure comprising a first oxide layer, a second oxide layer, and a metal layer stacked between the first oxide layer and the second oxide layer; patterning the second oxide layer; forming a mask layer on the patterned second oxide layer; introducing a gas mixture to the stacked structure; and performing a pulsing plasma process to the stacked structure through the mask layer to form at least one via running through the first oxide layer, the metal layer, and the second oxide layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. application Ser. No.17/452,769, filed on Oct. 28, 2021, which is herein incorporated byreference in its entirety.

BACKGROUND Field of Disclosure

The present disclosure relates to a method of manufacturing vias withpulsing plasma.

Description of Related Art

Semiconductor industries are developing and improving the manufacturingprocess for semiconductor structures, while the miniature of thecomponents continued. The accuracy of the scale and shape of thestructure thus become more important. To create vias in a semiconductorstructure, reaction ion etching methods are often used. The species ofthe ion particles are decided by the compounds of the plasma, whichneeds to consider the selective etching rate of the species of the ionparticles between different materials. Suitable prescription for theetching process is necessary and indispensable.

SUMMARY

The disclosure provides a method of manufacturing vias with pulsingplasma.

According to an embodiment of the present disclosure, a method ofmanufacturing a semiconductor includes: providing a stacked structurecomprising a first oxide layer, a second oxide layer, and a metal layerstacked between the first oxide layer and the second oxide layer;patterning the second oxide layer; forming a mask layer on the patternedsecond oxide layer; introducing a gas mixture to the stacked structure;and performing a pulsing plasma process to the stacked structure throughthe mask layer to form at least one via running through the first oxidelayer, the metal layer, and the second oxide layer.

In an embodiment of the present disclosure, the forming the mask layerincludes: forming a first covering layer on the patterned second oxidelayer; and forming a second covering layer on the first covering layerto cover and contact at least one portion of a surface of the metallayer.

In an embodiment of the present disclosure, the forming the secondcovering layer is performed by using a blanket deposition process.

In an embodiment of the present disclosure, the second covering layercomprises a high dielectric material.

In an embodiment of the present disclosure, the first covering layercomprises zirconium oxide or hafnium oxide.

In an embodiment of the present disclosure, the performing the pulsingplasma process further form at least one via running through the firstoxide layer, the metal layer, and the second oxide layer.

In an embodiment of the present disclosure, the gas mixture comprises atleast two hydrocarbon compounds and oxygen.

In an embodiment of the present disclosure, the at least two hydrocarboncompounds comprise a saturated hydrocarbon compound and an unsaturatedhydrocarbon compound or comprise two unsaturated hydrocarbon compounds.

In an embodiment of the present disclosure, one of the at least twohydrocarbon compounds has an additional double bond comparing to anotherone of the at least two hydrocarbon compounds.

In an embodiment of the present disclosure, the metal layer comprisestungsten.

According to an embodiment of the present disclosure, a method ofmanufacturing a semiconductor includes: providing a stacked structurecomprising a first oxide layer, a second oxide layer, and a metal layerstacked between the first oxide layer and the second oxide layer;forming a mask layer on the second oxide layer; introducing a gasmixture to the stacked structure, wherein the gas mixture comprises atleast two hydrocarbon compounds and oxygen; and performing a pulsingplasma process to the stacked structure through the mask layer topattern the second oxide layer and expose the metal layer through thepatterned second oxide layer, wherein the forming the mask layercomprises: forming a first covering layer on the second oxide layer;patterning the first covering layer to expose at least one portion of asurface of the second oxide layer; and forming a second covering layeron the patterned first covering layer to cover and contact the at leastone portion of the surface of the second oxide layer, wherein the secondcovering layer comprises a high dielectric material.

In an embodiment of the present disclosure, the forming the secondcovering layer is performed by using a blanket deposition process.

In an embodiment of the present disclosure, the first covering layercomprises zirconium oxide or hafnium oxide.

In an embodiment of the present disclosure, the performing the pulsingplasma process further form at least one via running through the firstoxide layer, the metal layer, and the second oxide layer.

In an embodiment of the present disclosure, the gas mixture comprises atleast two hydrocarbon compounds and oxygen.

In an embodiment of the present disclosure, the at least two hydrocarboncompounds comprise a saturated hydrocarbon compound and an unsaturatedhydrocarbon compound or comprise two unsaturated hydrocarbon compounds.

In an embodiment of the present disclosure, one of the at least twohydrocarbon compounds has an additional double bond comparing to anotherone of the at least two hydrocarbon compounds.

In an embodiment of the present disclosure, the metal layer comprisestungsten.

According to an embodiment of the present disclosure, a method ofmanufacturing a semiconductor includes: providing a stacked structurecomprising a first oxide layer, a second oxide layer, and a metal layerstacked between the first oxide layer and the second oxide layer;etching the second oxide layer; forming a mask layer on the second oxidelayer after etching the second oxide layer; and etching, using the masklayer as an etching mask, the metal layer and the first oxide layer toform at least one via.

In an embodiment of the present disclosure, the metal layer comprisestungsten.

It is to be understood that both the foregoing general description andthe following detailed description are by examples, and are intended toprovide further explanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be more fully understood by reading the followingdetailed description of the embodiment, with reference made to theaccompanying drawings as follows:

FIG. 1 is a flow chart of the method of manufacturing vias with pulsingplasma according to one embodiment of this disclosure.

FIG. 2A is a schematic diagram showing an intermediate stage of themethod according to one embodiment of this disclosure;

FIG. 2B is a schematic diagram showing an intermediate stage of themethod according to one embodiment of this disclosure;

FIG. 2C is a schematic diagram showing an intermediate stage of themethod according to one embodiment of this disclosure;

FIG. 2D is a schematic diagram showing an intermediate stage of themethod according to one embodiment of this disclosure;

FIG. 2E is a schematic diagram showing an intermediate stage of themethod according to one embodiment of this disclosure; and

FIG. 3 is an enlarge view of FIG. 2D according to one embodiment of thisdisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the present embodiments of thedisclosure, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

Reference is made to FIG. 1 . FIG. 1 is a flow chart of a method M1 ofmanufacturing vias with pulsing plasma according to one embodiment ofthis disclosure. As shown in FIG. 1 , the method M1 of manufacturingvias with pulsing plasma includes: providing a stacked structureincluding a first oxide layer, a second oxide layer, and a metal layerstacked between the first oxide layer and the second oxide layer (stepS110); forming a mask layer on the second oxide layer (step S120);introducing a gas mixture to the stacked structure, wherein the gasmixture includes at least two hydrocarbon compounds and oxygen (stepS130); and performing a pulsing plasma process to the stacked structurethrough the mask layer to pattern the second oxide layer and expose themetal layer through the patterned second oxide layer (step S140).

References are made to FIG. 2A and FIG. 1 . FIG. 2A is a schematicdiagram showing an intermediate stage of the method according to oneembodiment of this disclosure. As shown in FIG. 2A and FIG. 1 , astacked structure 110 is provided in step S110. The stacked structure110 is formed by sequentially stacking a first oxide layer 112, a metallayer 114, and a second oxide layer 116. In an embodiment, the metallayer 114 includes tungsten. In practical applications, the metal layer114 may include other metal. In some embodiments, the thickness of themetal layer 114 may be about 80 nm. In some embodiments, the thicknessratio of the first oxide layer 112, the metal layer 114, and the secondoxide layer 116 is 2:1:1. However, any suitable thickness of the firstoxide layer 112, the metal layer 114 and the second oxide layer 116 maybe utilized.

References are made to FIG. 2B and FIG. 1 . FIG. 2B is a schematicdiagram showing an intermediate stage of the method according to oneembodiment of this disclosure. As shown in FIG. 2B and FIG. 1 , a masklayer 120 is provided in step S120. The mask layer 120 may includemultiple sublayers, and different sublayers may be formed by usingdifferent processes. In an embodiment, step S120 includes: forming afirst covering layer on the second oxide layer (step S121); andpatterning the first covering layer to expose at least one portion of asurface of the second oxide layer (step S122). Specifically, in stepS121, the first covering layer 122 may be deposited over the secondoxide layer 116 by using any suitable deposition process, such aschemical vapor deposition, physical vapor deposition, the combination ofthereof, or the likes. In an embodiment, the first covering layer 122includes zirconium oxide or hafnium oxide, but the preset disclosure isnot limited to this. After the deposition of the first covering layer122, step S122 is performed in order to pattern the first covering layer122. The first covering layer 122 may be patterned by using, such as aphotolithography process, but the present disclosure is not limited tothis. Reference is made to FIG. 2B. In an embodiment, after the firstcovering layer 122 is patterned, the patterned first covering layer 122will expose some portions of the top surface of the second oxide layer116. The portions which are unexposed by the patterned first coveringlayer 122 may be protected by the patterned first covering layer 122until the patterned first covering layer 122 is fully removed.

Reference is made to FIG. 2B. Step S120 further includes: forming asecond covering layer on the patterned first covering layer to cover andcontact the at least one portion of the surface of the second oxidelayer (step S123). In an embodiment, the mask layer 120 includes a firstcovering layer 122 and a second covering layer 124, but the presentdisclosure is not limited to this. Any suitable number of the sublayersof the mask layer 120 may be utilized. In an embodiment, step S123 isperformed by using a blanket deposition process. The second coveringlayer 124 is conformally formed over the second oxide layer 116 and thefirst covering layer 122. Specifically, in FIG. 2B, the second coveringlayer 124 contacts with some portions of the top surface of the secondoxide layer 116 and the top surface and the sidewalls of the patternedfirst covering layer 122, but the present disclosure is not limited tothis. The second covering layer 124 may help to reduce the side etchingof the vias during the following pulsing plasma process, and thusenhance the straightness of the side walls of the vias. For example, instep S123, the second covering layer 124 is deposited by using, such asan atomic layer deposition process. In an embodiment, the secondcovering layer 124 includes a high dielectric material, but the presetdisclosure is not limited to this. The thickness of the mask layer 120(including the thickness of the first covering layer 122 and thethickness of the second covering layer 124) may be about 180 nm.However, any suitable thickness of the second covering layer 124 may beutilized.

Reference is made to FIG. 2C. FIG. 2C is a schematic diagram showing anintermediate stage of the method according to one embodiment of thisdisclosure. As shown in FIG. 2C and FIG. 1 , after forming the secondcovering layer 124, a gas mixture is introduced in step S130. The gasmixture is used for producing plasma with specific element and ioncompounds, which may provide a suitable selective etching rate betweenthe stacked structure 110 and the mask layer 120. The compounds of thegas mixture that is used for the following pulsing plasma process maymainly be decided by the etching rates thereof to the materials of themetal layer 114, the first covering layer 122, and the second coveringlayer 124. The gas mixture includes at least two hydrocarbon(C_(x)F_(y)) compounds and oxygen to provide a suitable selectiveetching rate between the metal layer 114 and the mask layer 120 (whichincludes the first covering layer 122 and the second covering layer124).

Specifically, in an embodiment, the at least two hydrocarbon compoundsinclude a saturated hydrocarbon compound and an unsaturated hydrocarboncompound or include two unsaturated hydrocarbon compounds. For example,the saturated hydrocarbon compound may be such as CF₄, or the likes, andthe unsaturated hydrocarbon compound may be such as C₄F₆, C₄F₈, or thelikes, but the present disclosure is not limited to this. Any suitablehydrocarbon compound that satisfies the definition of saturated orunsaturated may be utilized. The at least two hydrocarbon compounds thusmay be selected from the above gases, such as CF₄ and C₄F₆, which is anexample for the gas mixture with the combination of a saturatedhydrocarbon compound and an unsaturated hydrocarbon compound, orpossibly, a gas mixture including C₄F₆ and C₄F₈ provides an example forthe case in which the gas mixture includes two unsaturated hydrocarboncompounds. The ratio between the two or more compounds of the gasmixture may be decided according to the selective etching rate betweenthe materials of the mask layer 120 and the stacked structure 110, butany suitable compounds ratio may be utilized. In another embodiment, oneof the at least two hydrocarbon compounds has an additional double bondcomparing to another one of the at least two hydrocarbon compounds. Forexample, in an embodiment, the compound of the gas mixture may includeC₄F₈ and C₅F₈, in which C₄F₈ includes four single bonds between thecarbon elements, while C₅F₈ includes four single bonds and one doublebond between the carbon elements. However, any suitable hydrocarboncompound that satisfies the relation may be utilized.

References are made to FIG. 2C and FIG. 1 . After the gas mixture isintroduced, the pulsing plasma process is performed in step S140. Anelectric field is applied to the stacked structure 110, which mayattract the ion particles of the plasma moving along a direction andcollide with the stacked structure 110. The electric field may beprovided by applying a bias between two electrically separatedelectrodes. The electric intensity of the electric field may becontrolled by adjusting the bias which is applied on the electrodes. Forexample, pulsing biases applied on the electrodes may create pulsingelectric field utilized in the pulsing plasma process. The bias powermay be about 4000 W, but the present disclosure is not limited to this.Any suitable bias power may be utilized. While the electric field isapplied, the ion particles of the plasma will collide with the stackedstructure 110. More specifically, the ion particles will collide withthe mask layer 120 and the portions of the second oxide layer 116 whichare exposed by the mask layer 120. Taking tungsten as the material ofthe metal layer 114 for example, during applying electric field, thecollision between the tungsten and the ion particles produces highlyvolatile reactants, such as WF₆, or the likes, which will be pumped outby a gas pump. One of the reasons for choosing pulsing plasma to etchthe stacked structure 110 is to better control the etching process byreducing any uncontrollable particles (such as reactant particles) thatwill leads to unwanted etching profile.

Reference is made to FIG. 2D. FIG. 2D is a schematic diagram showing anintermediate stage of the method according to one embodiment of thisdisclosure. As shown in FIG. 2D, the etching process of the method M1may include multiple pulsing plasma processes, and each pulsing plasmaprocess may aim to etch different layers of the stacked structure 110,but the present disclosure is not limited to this. For example, in anembodiment, the method M1 further includes: forming another mask layeron the patterned second oxide layer (step S150); and performing anotherpulsing plasma process to the stacked structure through the another masklayer to form at least one via running through the first oxide layer,the metal layer, and the second oxide layer (step S160). The reason toperform multiple steps of pulsing plasma is to develop a suitableprescription of the gas mixture and the parameters that are used duringthe pulsing plasma process for providing vias with highly straightnesssidewalls, but the present disclosure is not limited to this.

Specifically, after the second oxide layer 116 is etched by the firstpulsing plasma process as shown in FIG. 2C, another mask layer 130 isformed over the patterned second oxide layer 116. In an embodiment, stepS150 includes: forming another first covering layer on the patternedsecond oxide layer (step S151); and forming another second coveringlayer on the another first covering layer to cover and contact at leastone portion of a surface of the metal layer (step S152). For example,the another mask layer 130 may also include multiple sublayers, such asthe another first covering layer 132 and the another second coveringlayer 134 which are shown in FIG. 2D. The formation of the another firstcovering layer 132 and the another second covering layer 134 may besimilar or the same as the formation of the first covering layer 122 andthe second covering layer 124 described above, but the presentdisclosure is not limited to this. Any suitable process may be utilized.Additionally, the materials and the thicknesses of the another firstcovering layer 132 and the another second covering layer 134 may besimilar or the same as those of the first covering layer 122 and thesecond covering layer 124 described above. For example, in anembodiment, the another first covering layer 132 includes zirconiumoxide or hafnium oxide. However, any suitable materials and thicknessesmay be utilized.

References are made to FIG. 2D and FIG. 3 . FIG. 3 is an enlarge view ofFIG. 2D according to one embodiment of this disclosure. As shown in FIG.2D and FIG. 3 , the another mask layer 130 is formed over the stackedstructure 110.

Specifically, in an embodiment, the another second covering layer 134 isperformed by using a blanket deposition process. The another secondcovering layer 134 is conformally formed over the second oxide layer 116and the another first covering layer 132. Specifically, in FIG. 2D, theanother second covering layer 134 contacts with some portions of the topsurface of the metal layer 114 and the top surface and the sidewalls ofthe another first covering layer 132 and the second oxide layer 116, butthe present disclosure is not limited to this. The another secondcovering layer 134 may help to reduce the side etching during thefollowing pulsing plasma process, and thus enhance the straightness ofthe side walls of the vias. For example, the another second coveringlayer 134 is deposited by using, such as an atomic layer depositionprocess. In an embodiment, the another second covering layer 134includes a high dielectric material, but the preset disclosure is notlimited to this.

Specifically, in FIG. 3 , the left sidewall and the right side wall ofthe opening 140 are defined by the first side wall 142 and the secondside wall 144 respectively, and the bottom wall 146 of the opening 140is defined by the top surface of the metal layer 114 which is exposed bythe another first covering layer 132 and the second oxide layer 116. Thetop surface of the another first covering layer 132, the first side wall142, the second side wall 144, and the bottom wall 146 are covered bythe another second covering layer 134. The another first covering layer132 and the another second covering layer 134 protect the patternedsecond oxide layer 116 and portions of the metal layer 114 and the firstoxide layer 112 beneath. The adopted pulsing plasma process may be ananisotropic etching process, which may has higher etching rate along onecertain direction (such as a first direction A1), while has less etchingrate in other directions (such as a second direction A2). During thepulsing plasma process, surface etching is achieved by the collisionsbetween the ion particles and the surface of the stacked structure 110.In the embodiment as shown in FIG. 3 , the first direction A1 may beperpendicular to the top surface of the another first covering layer 132and the bottom wall 146, while the second direction A2 may beperpendicular to the first side wall 142 and the second side wall 144.The portions of the stacked structure 110 which are covered by the masklayer 130 may be retained after the etching process. However, theportions exposed by the opening 140 are only protected by the anothersecond covering layer 134 and may be etched more or less during theprocedure. The another second covering layer 134 can protect the firstside wall 142 and the second side wall 144 from side etching, thus toimprove the straightness of the side walls, while letting the ionparticles to collide with the bottom wall 146 and extend the opening 140through the metal layer 114 and the first oxide layer 112. The topsurface of the second oxide layer 116 is protected by the another firstcovering layer 132 and the another second covering layer 134, and thuswill be retained after the etching process.

Reference is made to FIG. 2E. FIG. 2E is a schematic diagram showing anintermediate stage of the method according to one embodiment of thisdisclosure. As shown in FIG. 2E, after finishing multiple pulsing plasmaprocesses, vias 150 that penetrate through the stacked structure 110 areformed. In an embodiment, step S160 further forms at least one viarunning through the first oxide layer 112, the metal layer 114, and thesecond oxide layer 116. Further, after confirming the suitableprescription of the gas mixture and the parameters that are used duringthe pulsing plasma process, the multiple pulsing plasma processes may besimplified to one pulsing plasma process, and thus reduce the cost ofmanufacturing. The one-time execution of the pulsing plasma process maybe similar to or the same as the pulsing plasma process described above.However, any suitable methods can be utilized.

Although the present disclosure has been described in considerabledetail with reference to certain embodiments thereof, other embodimentsare possible. Therefore, the spirit and scope of the appended claimsshould not be limited to the description of the embodiments containedherein.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentdisclosure without departing from the scope or spirit of the disclosure.In view of the foregoing, it is intended that the present disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims.

What is claimed is:
 1. A method of manufacturing a semiconductor,comprising: providing a stacked structure comprising a first oxidelayer, a second oxide layer, and a metal layer stacked between the firstoxide layer and the second oxide layer; patterning the second oxidelayer; forming a mask layer on the patterned second oxide layer;introducing a gas mixture to the stacked structure; and performing apulsing plasma process to the stacked structure through the mask layerto form at least one via running through the first oxide layer, themetal layer, and the second oxide layer.
 2. The method of claim 1,wherein the forming the mask layer comprises: forming a first coveringlayer on the patterned second oxide layer; and forming a second coveringlayer on the first covering layer to cover and contact at least oneportion of a surface of the metal layer.
 3. The method of claim 2,wherein the forming the second covering layer is performed by using ablanket deposition process.
 4. The method of claim 2, wherein the secondcovering layer comprises a high dielectric material.
 5. The method ofclaim 2, wherein the first covering layer comprises zirconium oxide orhafnium oxide.
 6. The method of claim 1, wherein the performing thepulsing plasma process further form at least one via running through thefirst oxide layer, the metal layer, and the second oxide layer.
 7. Themethod of claim 1, wherein the gas mixture comprises at least twohydrocarbon compounds and oxygen.
 8. The method of claim 7, wherein theat least two hydrocarbon compounds comprise a saturated hydrocarboncompound and an unsaturated hydrocarbon compound or comprise twounsaturated hydrocarbon compounds.
 9. The method of claim 7, wherein oneof the at least two hydrocarbon compounds has an additional double bondcomparing to another one of the at least two hydrocarbon compounds. 10.The method of claim 1, wherein the metal layer comprises tungsten.
 11. Amethod of manufacturing a semiconductor, comprising: providing a stackedstructure comprising a first oxide layer, a second oxide layer, and ametal layer stacked between the first oxide layer and the second oxidelayer; forming a mask layer on the second oxide layer; introducing a gasmixture to the stacked structure, wherein the gas mixture comprises atleast two hydrocarbon compounds and oxygen; and performing a pulsingplasma process to the stacked structure through the mask layer topattern the second oxide layer and expose the metal layer through thepatterned second oxide layer, wherein the forming the mask layercomprises: forming a first covering layer on the second oxide layer;patterning the first covering layer to expose at least one portion of asurface of the second oxide layer; and forming a second covering layeron the patterned first covering layer to cover and contact the at leastone portion of the surface of the second oxide layer, wherein the secondcovering layer comprises a high dielectric material.
 12. The method ofclaim 11, wherein the forming the second covering layer is performed byusing a blanket deposition process.
 13. The method of claim 11, whereinthe first covering layer comprises zirconium oxide or hafnium oxide. 14.The method of claim 11, wherein the performing the pulsing plasmaprocess further form at least one via running through the first oxidelayer, the metal layer, and the second oxide layer.
 15. The method ofclaim 11, wherein the gas mixture comprises at least two hydrocarboncompounds and oxygen.
 16. The method of claim 15, wherein the at leasttwo hydrocarbon compounds comprise a saturated hydrocarbon compound andan unsaturated hydrocarbon compound or comprise two unsaturatedhydrocarbon compounds.
 17. The method of claim 15, wherein one of the atleast two hydrocarbon compounds has an additional double bond comparingto another one of the at least two hydrocarbon compounds.
 18. The methodof claim 11, wherein the metal layer comprises tungsten.
 19. A method ofmanufacturing a semiconductor, comprising: providing a stacked structurecomprising a first oxide layer, a second oxide layer, and a metal layerstacked between the first oxide layer and the second oxide layer;etching the second oxide layer; forming a mask layer on the second oxidelayer after etching the second oxide layer; and etching, using the masklayer as an etching mask, the metal layer and the first oxide layer toform at least one via.
 20. The method of claim 19, wherein the metallayer comprises tungsten.